Agricultural combines are large machines that harvest, thresh, separate and clean agricultural crops that bear grain. The clean grain obtained is stored in a grain tank arranged on the combine. The threshed straw is generally chopped and spread out on the field across the width of the chopping mechanism.
In one common arrangement, grain is passed through a series of screens which are arranged to permit chaff to be blown away. The clean grain falls down to the bottom of the agricultural combine in a shallow trough. This trough extends laterally from side to side across the width of the agricultural combine and houses an elongate auger that draws the grain to one side of the combine and through an aperture in the side wall of the combine. Typically, a short transition tube is attached to the side wall of the combine and extending outward therefrom supports a short length of the auger and helps convey the grain in the bottom of the trough to the lower inlet portion of a paddle elevator that lifts the grain into a grain tank onboard the combine for later offloading to a vehicle traveling alongside.
As the harvesting capacity of agricultural combines increases, the amount of grain that must be carried by the auger and by the paddle elevator increases as well. One problem with the augers is that they are limited in the speed they can rotate and in their overall size. What is needed is a way of increasing the flow rate without increasing the outer diameter of the auger.
U.S. Pat. No. 6,053,811 illustrates a clean grain auger disposed at the lower portion of the combine and paddle elevator for lifting the grain up to the grain tank. In this embodiment, a short tubular section is provided to support the auger and carry the grain between the trough (see FIG. 1) and the paddle elevator (see FIG. 2). The tubular section is slightly ovoid in cross-section as best shown in FIG. 4. This ovoid shape permits a mechanical grain flow sensor to be inserted inside the short tubular section. This shows the sharp transition from the body of the agricultural combine at the entrance of the transition tube, which is almost exactly the same diameter as the helical auger flights it surrounds.
U.S. Pat. No. 6,350,197 illustrates a clean grain auger having a similar short tubular transition section. The short transition section is coupled to a circular aperture in the bottom of the paddle elevator. This traditional aperture and transition tube significantly disrupts grain low by the sharp entrance to the transition tube.